These are a series of pictures taken throughout the process of making a ring with my most commonly used technique.
These pictures were taken with an old camera, so they are not high-resolution, but should be enough to illustrate the process.
(tip: If this page isn't sorted by date in descending order, the pictures will be out of chronological order)
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It all begins with the raw materials. I use preferentially casting grain, little gold pellets, provided to me by my refiner of choice.
I used 14k rose gold for this ring, thus the red-ish tone of the gold.

My prefered casting method is the Cuttlebone Technique, because of the sheer simplicity of it. Take a cuttlebone (the calcareous internal shell of a cuttlefish) of appropriate size, cut it in half, flatten and smooth the surfaces, carve on the soft surface a negative of the shape of the ring, bind the halves together with wire, voilą!, you got yourself a mold that surprisingly will endure the high temperatures of molten gold. To me it casts cleaner than pre-made iron molds and doesn't require expensive special equipment like the Centrifugal Lost Wax Casting Process does. It has its draw-backs though: It's very challenging to cast complex 3D shapes, the mold is always destroyed in the process, and if something goes wrong in the casting, you have to make a whole new mold.
To me, the fact that the mold is always destroyed isn't that big of a problem, because I deal mostly with unique pieces of jewelry. So, you will never see someone with an item alike yours if I made them with the Cuttlebone Technique.
Geek Note: Have you watched The Lord of the Rings? In the beginning when she's talking about the forging of the Great Rings of Power, the casting they show is a cuttlebone casting. :)
In this picture, you can see the negative impression of the ring on the cuttlebone, and those lines coming from it are the spur hole through which the molten metal will be poured into the mold, and vent channels so that the gases that will form in the mold can escape thus allowing the gold to fill in the empty spaces.

Aim the blue flame 'A' at the gold 'B' in the crucible 'C' and the gold will melt. Add a pinch of borax 'D' at specific times during the melting process to prevent the copper in the gold alloy from absorbing oxygen and altering the color of the gold.

That's what the ring looks like just out of the mold (after being rinsed with water). The thick nub is where the gold was poured into the mold, and the small 'antennas' are where gold flowed into the venting channels, which is a good sign that the gold was fluid enough to fill in every tiny space. The channels in the mold are designed so that metal can flow into them but will never leak from the mold. They will all be cut off to fine-tune the shape of the ring of course.

The spurs from the mold are cut off, the ring is properly stretched and made perfectly round on the sizing mandrel, then the final shape is refined with jeweler files and a lot of patience and precision.

I regularly check the size of the ring as I work with files on it, to make sure I'm not taking away too much metal from the insides.
Once the surface is 'clean' enough and the ring is at the intended shape, I use emery paper (fancy name for 'sandpaper') of different grit, from 300 to 600, to remove any scratches left on the metal by the files. Then comes polishing with polishing compound.